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IP addressing: Next wave

While you probably know that the IETF drafted an IPv6 specification for the next generation of the Internet Protocol, you may not be familiar with its specifics--or why it's important to enterprises.
Written by Lee Schlesinger, Contributor
IPv6 increases IP address space to 128 bits, thus increasing the pool of addresses from IPv4's 2^32 to 2^128, or 340,282,366,920,938,463,463,374,607,431,768,211,456--a high number commonly referred to as "plenty." IPv6 also simplifies IP headers to improve packet handling. Even though IPv6 addresses are four times longer than IPv4's 32-bit addresses, IPv6 packet headers are only twice the size of IPv4's.

Throughput is always an issue where network traffic is concerned. Network pipes are more likely to become clogged as traffic from more devices traverses them. IPv6 adds quality-of-service (QoS) capabilities, so senders can request, and devices can apply, special handling to different kinds of traffic. That's something bandwidth management devices like Packeteer's PacketShaper can do today by deducing traffic characteristics from packet headers. Making QoS information explicit will help routers process packets more quickly, making it easier, for example, to give real-time multimedia higher than default QoS, while simple file transfers might get lower.

IPv6 also includes provisions for extensions, which are optional header elements within each packet, placed between the transport layer header and the IP header. Routers along a packet's path can ignore extension headers, making them an efficient way to add capabilities relevant only at a packet's destination. The current IPv6 spec defines extensions for extended routing, meaning you can specify an explicit route from source to destination; fragmentation, which lets destination routers reassemble fragmented packets more easily; authentication, to ensure a packet has not been altered while in transit; and encapsulation (data privacy), among others.

Those are the major differences between IPv4 and IPv6 packets, in a nutshell. Read Robert M. Hinden's paper or Adrian Estala's Web page for additional information about the IPv6 spec.

You don't need to worry about converting your network to IPv6 this year. But Gartner predicts that vendors will have related products widely available in the 2005-2008 timeframe. What can you do until then? Plan for IPv6 by trying to purchase networking hardware whose firmware will be capable of being upgraded to the new protocol, if it's not already. That may not be necessary, given the far horizon for widespread IPv6 implementation and the average effective life of networking hardware, but it pays to be prudent. Microsoft expects to support IPv6 in its XP client and .Net Server protocol stacks in upcoming releases; a developer-oriented version of IPv6 is available for XP today. Similar projects are underway for Linux and other operating systems. You can keep up with IPv6 developments at hs247.com.

Some vendors have already taken IPv6 action. Last year, Cisco Systems added support for IPv6 to version 12.2(1)T of its IOS software. Microsoft just gave IPv6 a boost by urging attendees at its WinHEC conference to "build native support for IPv6 in every application [and] piece of hardware." Other hardware and software vendors are working on their own implementations. A Next Generation Transition Working Group is working to assist the industry with the transition from IPv4 to IPv6.

You can already get your own IPv6 addresses from the American Registry for Internet Numbers if you can prove you need them. But don't feel you have to hurry--we're not about to run out of addresses. There are many times more addresses available than the total number of humans who ever lived, or the number of square inches of Earth's surface. Or, in technical terms, plenty.

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